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Basic knowledge of SMA coaxial cables: A detailed explanation of their structure and characteristics
SMA coaxial cables are important communication devices that are essential for transmitting high frequency signals. Due to their small size and excellent performance, they are used in a wide range of fields, from communication equipment to the aerospace industry.
This article will explain in detail the characteristics of SMA coaxial cables and how they differ from other connectors. It will be a valuable source of information for those who are interested in high-frequency communication technology or who may use it in their work. Please read it for reference.
What is SMA coaxial cable?
SMA coaxial cable is specialized for transmitting high frequency signals. SMA stands for Sub-Miniature version A and has a connector that allows for a small and high performance connection. Therefore, it is widely used in various fields that handle high frequency signals, such as wireless communication equipment, test and measurement equipment, and satellite communication systems.
SMA coaxial cables are characterized by their excellent electrical performance despite their small size. They are suitable for use in high frequency bands, and provide stable transmission with minimal signal loss. They are also highly durable and resistant to repeated connections and disconnections, making them suitable for use in environments where long-term use or frequent equipment replacement is required.
Basic structure of SMA coaxial cable
The basic structure of an SMA coaxial cable consists of four main parts, just like a regular coaxial cable. At the center is the central conductor that transmits the signal, which is surrounded by an insulator. Outside the insulator is the outer conductor (shield), and the outermost layer is the outer jacket.
The central conductor is typically made of copper or silver-plated copper wire to ensure high electrical conductivity, while the insulator is made of low-loss materials such as Teflon (PTFE) to minimize signal attenuation.
The outer conductor is made of braided copper wire or aluminum foil, which protects the signal from electromagnetic interference, while the outer coating is made of heat-resistant and weather-resistant polyethylene or PVC, which protects the entire cable from physical damage.
The difference between SMA and SMB
The main difference between SMA and SMB is their size and applications. SMA connectors are relatively small and have a wide frequency range, up to 18GHz. Therefore, they are commonly used in wireless communication equipment and measurement equipment. SMB connectors, on the other hand, are even smaller and have a frequency range up to about 4GHz. SMBs are often used in applications with relatively low frequency connections, making them more suitable for smaller devices and tighter spaces than SMAs.
There are also differences in the connection methods: SMA connectors use a screw-type connection that provides a secure connection and better electrical performance, while SMB connectors use a snap-on mechanism that allows for quick connection and disconnection, but SMA is more resistant to vibration and shock.
Functional Classification of SMA Coaxial Connectors
An SMA coaxial connector is a part used to connect cables to devices. SMA coaxial connectors are mainly divided into four functional categories. Let's take a closer look at the features of each.
plug
The SMA plug is a connector that corresponds to the male terminal of a coaxial cable and is responsible for sending signals to the connected destination. The plug is a screw-in type, and is characterized by high connection stability. The plug has a protruding central conductor, which is connected to the jack side to enable signal transmission.
SMA plugs are widely used in wireless communications and high-precision measuring instruments, and their excellent mechanical strength makes them ideal for connections that require long-term reliability.
ジ ャ ッ ク
The SMA jack is a connector that is equivalent to the female terminal of a coaxial cable. The jack is used in combination with a plug to receive the signal sent from the plug. The SMA jack is screwed in like the plug and is firmly fixed in place, ensuring stability during signal transmission.
Jacks are usually attached to the side of equipment and are often used to ensure a secure connection between the device and the cable.
Receptacle
A receptacle is a part of an SMA connector, and unlike a plug or jack, it plays an intermediate role for connecting to other connectors. It is usually attached to equipment or cables and supports the connection with a plug or jack. Receptacles are often used in environments where plugs and jacks are frequently removed, to increase their durability and maintain stability when connected.
adapter
The SMA adapter is a conversion tool that enables connections between different types of connectors. It can convert between SMA connectors as well as other connector standards (such as SMB and BNC), providing flexible support for connections between a variety of devices.
Adapters are very useful for increasing system expandability and integrating devices with different standards. The advantage of SMA adapters is that they provide high compatibility while minimizing signal loss.
SMA Coaxial Cable Applications
SMA coaxial cables are widely used in a variety of high frequency communication and measurement applications.
In the communications field, it is used to connect mobile phone base stations and wireless LAN antennas. Its ability to transmit high-frequency signals with low loss also contributes to maintaining communication quality. It also plays an important role in new technologies such as 5G communications.
SMA coaxial cables are small and highly efficient, allowing them to be flexibly installed even in tight spaces. In the measuring instrument field, they are used in precision instruments such as network analyzers and spectrum analyzers. Because they are capable of accurate measurements in high frequency bands, they are used in research and development and quality control.
How to connect SMA coaxial cable
The connection of SMA coaxial cable is made using a screw-type connector.
First, check that the cable and connector are clean. Dirt or foreign matter can cause poor connection, so wipe them off with alcohol or other cleaning agents if necessary.
Next, insert the plug into the jack, being careful not to bend the center pin. Then, rotate the plug clockwise to screw it in firmly, but be careful not to overtighten it, as this can damage the connector.
After connecting, wire the cable so that it is not subjected to excessive force. It is especially important to pay attention to the bending radius of the cable and to avoid sharp bending. Also, periodically check that the connections are not loose, and retighten them if necessary.
SMA Coaxial Cable Types
There are various types of SMA coaxial cables depending on the application and environment. The main classifications are impedance, frequency band, shielding performance, etc.
There are two common impedance types: 50Ω and 75Ω. The 2Ω type is primarily used in communication devices and measuring instruments, while the 50Ω type is used for transmitting video signals.
There is a wide range of frequency bands, from low to high frequencies. A typical SMA coaxial cable can handle frequencies up to 18 GHz, but there are some special ones that can handle frequencies up to 26.5 GHz.
There are single shield, double shield, triple shield, etc. The more layers of shielding, the stronger the resistance to external electromagnetic interference, but at the same time, the less flexible the cable is.
We offer coaxial cable assemblies that can be used in the microwave band and are compatible with SMA connectors.
The products with the connector symbols "SMA-P" and "SMA-J" in the connector/cable combination table on the following page use SMA connectors.
Summary
There are various types of SMA coaxial cables depending on the usage environment and the required frequency band. By understanding the correct knowledge and appropriate selection, you can achieve a better signal transmission environment and maximize the performance of your equipment.
By understanding its characteristics and using it appropriately, it will be possible to build advanced communication systems and precise measurement environments.
